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update docs examples which use build-exe to be tested

See #465
This commit is contained in:
Andrew Kelley 2018-01-17 03:24:03 -05:00
parent 7a3fd89d25
commit 2e6125bc66
3 changed files with 30 additions and 783 deletions
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9
build.zig
View File

@ -24,17 +24,8 @@ pub fn build(b: &Builder) -> %void {
});
docgen_cmd.step.dependOn(&docgen_exe.step);
var docgen_home_cmd = b.addCommand(null, b.env_map, [][]const u8 {
docgen_exe.getOutputPath(),
rel_zig_exe,
"doc/home.html.in",
os.path.join(b.allocator, b.cache_root, "home.html") catch unreachable,
});
docgen_home_cmd.step.dependOn(&docgen_exe.step);
const docs_step = b.step("docs", "Build documentation");
docs_step.dependOn(&docgen_cmd.step);
docs_step.dependOn(&docgen_home_cmd.step);
const test_step = b.step("test", "Run all the tests");

724
doc/home.html.in
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@ -1,724 +0,0 @@
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, user-scalable=no" />
<title>The Zig Programming Language</title>
<link rel="stylesheet" type="text/css" href="highlight/styles/default.css">
<style type="text/css">
img {
max-width: 100%;
}
</style>
</head>
<body>
<img src="zig-logo.svg">
<p>
Zig is an open-source programming language designed for <strong>robustness</strong>,
<strong>optimality</strong>, and <strong>clarity</strong>.
</p>
<p>
<a href="download/">Download</a> |
<a href="documentation/master/">Documentation</a> |
<a href="https://github.com/zig-lang/zig">Source Code</a> |
<a href="https://github.com/zig-lang/zig/issues">Bug Tracker</a> |
<a href="https://webchat.freenode.net/?channels=%23zig">IRC</a> |
<a href="https://www.patreon.com/andrewrk">Donate $1/month</a>
</p>
<h2>Feature Highlights</h2>
<ul>
<li>Manual memory management. Memory allocation failure is handled correctly. Edge cases matter!</li>
<li>Zig competes with C instead of depending on it. The Zig Standard Library does not depend on libc.</li>
<li>Small, simple language. Focus on debugging your application rather than debugging your knowledge of your programming language.</li>
<li>A fresh take on error handling that resembles what well-written C error handling looks like,
minus the boilerplate and verbosity.</li>
<li>Debug mode optimizes for fast compilation time and crashing with a stack trace when undefined behavior
<em>would</em> happen.</li>
<li>ReleaseFast mode produces heavily optimized code. What other projects call
"Link Time Optimization" Zig does automatically.</li>
<li>ReleaseSafe mode produces optimized code but keeps safety checks enabled. Disable safety checks in the bottlenecks of your code.</li>
<li>Generic data structures and functions.</li>
<li>Compile-time reflection and compile-time code execution.</li>
<li>Import .h files and directly use C types, variables, and functions.</li>
<li>Export functions, variables, and types for C code to depend on. Automatically generate .h files.</li>
<li>Nullable type instead of null pointers.</li>
<li>Order independent top level declarations.</li>
<li>Friendly toward package maintainers. Reproducible build, bootstrapping process carefully documented. Issues filed by package maintainers are considered especially important.</li>
<li>Cross-compiling is a first-class use case.</li>
<li>No preprocessor. Instead Zig has a few carefully designed features that
provide a way to accomplish things you might do with a preprocessor.</li>
</ul>
<h2 id="reading-material">Reading Material</h2>
<ul>
<li>2018-01-03 - <a href="http://andrewkelley.me/post/zig-december-2017-in-review.html">December 2017 in Review</a></li>
<li>2017-10-17 - <a href="download/0.1.1/release-notes.html">Zig 0.1.1 Release Notes</a></li>
<li>2017-07-19 - <a href="http://tiehuis.github.io/iterative-replacement-of-c-with-zig">Iterative Replacement of C with Zig</a></li>
<li>2017-02-16 - <a href="http://andrewkelley.me/post/a-better-way-to-implement-bit-fields.html">A Better Way to Implement Bit-Fields</a></li>
<li>2017-02-13 - <a href="http://andrewkelley.me/post/zig-already-more-knowable-than-c.html">Zig: Already More Knowable Than C</a></li>
<li>2017-01-30 - <a href="http://andrewkelley.me/post/zig-programming-language-blurs-line-compile-time-run-time.html">Zig Programming Language Blurs the Line Between Compile-Time and Run-Time</a></li>
<li>2016-02-08 - <a href="http://andrewkelley.me/post/intro-to-zig.html">Introduction to the Zig Programming Language</a></li>
</ul>
<h2 id="source-examples">Source Code Examples</h2>
<ul>
<li><a href="#hello">Hello World</a></li>
<li><a href="#hello_libc">Hello World with libc</a></li>
<li><a href="#parse">Parsing Unsigned Integers</a></li>
<li><a href="#hashmap">HashMap with Custom Allocator</a></li>
<li><a href="#tetris">Tetris Clone</a></li>
<li><a href="#clashos">Bare Bones Operating System</a></li>
<li><a href="#cat">Cat Utility</a></li>
<li><a href="#multiline-strings">Multiline String Syntax</a></li>
<li><a href="#mersenne">Mersenne Twister Random Number Generator</a></li>
</ul>
<h3 id="hello">Hello World</h3>
<pre><code class="zig">const std = @import("std");
pub fn main() -&gt; %void {
// If this program is run without stdout attached, exit with an error.
var stdout_file = try std.io.getStdOut();
// If this program encounters pipe failure when printing to stdout, exit
// with an error.
try stdout_file.write("Hello, world!\n");
}</code></pre>
<p>Build this with:</p>
<pre>zig build-exe hello.zig</pre>
<h3 id="hello_libc">Hello World with libc</h3>
<pre><code class="zig">const c = @cImport({
// See https://github.com/zig-lang/zig/issues/515
@cDefine("_NO_CRT_STDIO_INLINE", "1");
@cInclude("stdio.h");
@cInclude("string.h");
});
const msg = c"Hello, world!\n";
export fn main(argc: c_int, argv: &amp;&amp;u8) -&gt; c_int {
if (c.printf(msg) != c_int(c.strlen(msg)))
return -1;
return 0;
}</code></pre>
<p>Build this with:</p>
<pre>zig build-exe hello.zig --library c</pre>
<h3 id="parse">Parsing Unsigned Integers</h3>
<pre><code class="zig">pub fn parseUnsigned(comptime T: type, buf: []u8, radix: u8) -&gt; %T {
var x: T = 0;
for (buf) |c| {
const digit = try charToDigit(c, radix);
x = try mulOverflow(T, x, radix);
x = try addOverflow(T, x, digit);
}
return x;
}
error InvalidChar;
fn charToDigit(c: u8, radix: u8) -&gt; %u8 {
const value = switch (c) {
'0' ... '9' =&gt; c - '0',
'A' ... 'Z' =&gt; c - 'A' + 10,
'a' ... 'z' =&gt; c - 'a' + 10,
else =&gt; return error.InvalidChar,
};
if (value &gt;= radix)
return error.InvalidChar;
return value;
}
error Overflow;
pub fn mulOverflow(comptime T: type, a: T, b: T) -&gt; %T {
var answer: T = undefined;
if (@mulWithOverflow(T, a, b, &amp;answer)) error.Overflow else answer
}
pub fn addOverflow(comptime T: type, a: T, b: T) -&gt; %T {
var answer: T = undefined;
if (@addWithOverflow(T, a, b, &amp;answer)) error.Overflow else answer
}
fn getNumberWithDefault(s: []u8) -&gt; u32 {
parseUnsigned(u32, s, 10) catch 42
}
fn getNumberOrCrash(s: []u8) -&gt; u32 {
%%parseUnsigned(u32, s, 10)
}
fn addTwoTogetherOrReturnErr(a_str: []u8, b_str: []u8) -&gt; %u32 {
const a = parseUnsigned(u32, a_str, 10) catch |err| return err;
const b = parseUnsigned(u32, b_str, 10) catch |err| return err;
return a + b;
}</code></pre>
<h3 id="hashmap">HashMap with Custom Allocator</h3>
<pre><code class="zig">const debug = @import(&quot;debug.zig&quot;);
const assert = debug.assert;
const math = @import(&quot;math.zig&quot;);
const mem = @import(&quot;mem.zig&quot;);
const Allocator = mem.Allocator;
const want_modification_safety = !@compileVar(&quot;is_release&quot;);
const debug_u32 = if (want_modification_safety) u32 else void;
pub fn HashMap(comptime K: type, comptime V: type, comptime hash: fn(key: K)-&gt;u32,
comptime eql: fn(a: K, b: K)-&gt;bool) -&gt; type
{
struct {
entries: []Entry,
size: usize,
max_distance_from_start_index: usize,
allocator: &amp;Allocator,
// this is used to detect bugs where a hashtable is edited while an iterator is running.
modification_count: debug_u32,
const Self = this;
pub const Entry = struct {
used: bool,
distance_from_start_index: usize,
key: K,
value: V,
};
pub const Iterator = struct {
hm: &amp;Self,
// how many items have we returned
count: usize,
// iterator through the entry array
index: usize,
// used to detect concurrent modification
initial_modification_count: debug_u32,
pub fn next(it: &amp;Iterator) -&gt; ?&amp;Entry {
if (want_modification_safety) {
assert(it.initial_modification_count == it.hm.modification_count); // concurrent modification
}
if (it.count &gt;= it.hm.size) return null;
while (it.index &lt; it.hm.entries.len) : (it.index += 1) {
const entry = &amp;it.hm.entries[it.index];
if (entry.used) {
it.index += 1;
it.count += 1;
return entry;
}
}
unreachable // no next item
}
};
pub fn init(hm: &amp;Self, allocator: &amp;Allocator) {
hm.entries = []Entry{};
hm.allocator = allocator;
hm.size = 0;
hm.max_distance_from_start_index = 0;
// it doesn't actually matter what we set this to since we use wrapping integer arithmetic
hm.modification_count = undefined;
}
pub fn deinit(hm: &amp;Self) {
hm.allocator.free(Entry, hm.entries);
}
pub fn clear(hm: &amp;Self) {
for (hm.entries) |*entry| {
entry.used = false;
}
hm.size = 0;
hm.max_distance_from_start_index = 0;
hm.incrementModificationCount();
}
pub fn put(hm: &amp;Self, key: K, value: V) -&gt; %void {
if (hm.entries.len == 0) {
try hm.initCapacity(16);
}
hm.incrementModificationCount();
// if we get too full (60%), double the capacity
if (hm.size * 5 &gt;= hm.entries.len * 3) {
const old_entries = hm.entries;
try hm.initCapacity(hm.entries.len * 2);
// dump all of the old elements into the new table
for (old_entries) |*old_entry| {
if (old_entry.used) {
hm.internalPut(old_entry.key, old_entry.value);
}
}
hm.allocator.free(Entry, old_entries);
}
hm.internalPut(key, value);
}
pub fn get(hm: &amp;Self, key: K) -&gt; ?&amp;Entry {
return hm.internalGet(key);
}
pub fn remove(hm: &amp;Self, key: K) {
hm.incrementModificationCount();
const start_index = hm.keyToIndex(key);
{var roll_over: usize = 0; while (roll_over &lt;= hm.max_distance_from_start_index) : (roll_over += 1) {
const index = (start_index + roll_over) % hm.entries.len;
var entry = &amp;hm.entries[index];
assert(entry.used); // key not found
if (!eql(entry.key, key)) continue;
while (roll_over &lt; hm.entries.len) : (roll_over += 1) {
const next_index = (start_index + roll_over + 1) % hm.entries.len;
const next_entry = &amp;hm.entries[next_index];
if (!next_entry.used or next_entry.distance_from_start_index == 0) {
entry.used = false;
hm.size -= 1;
return;
}
*entry = *next_entry;
entry.distance_from_start_index -= 1;
entry = next_entry;
}
unreachable // shifting everything in the table
}}
unreachable // key not found
}
pub fn entryIterator(hm: &amp;Self) -&gt; Iterator {
return Iterator {
.hm = hm,
.count = 0,
.index = 0,
.initial_modification_count = hm.modification_count,
};
}
fn initCapacity(hm: &amp;Self, capacity: usize) -&gt; %void {
hm.entries = try hm.allocator.alloc(Entry, capacity);
hm.size = 0;
hm.max_distance_from_start_index = 0;
for (hm.entries) |*entry| {
entry.used = false;
}
}
fn incrementModificationCount(hm: &amp;Self) {
if (want_modification_safety) {
hm.modification_count +%= 1;
}
}
fn internalPut(hm: &amp;Self, orig_key: K, orig_value: V) {
var key = orig_key;
var value = orig_value;
const start_index = hm.keyToIndex(key);
var roll_over: usize = 0;
var distance_from_start_index: usize = 0;
while (roll_over &lt; hm.entries.len) : ({roll_over += 1; distance_from_start_index += 1}) {
const index = (start_index + roll_over) % hm.entries.len;
const entry = &amp;hm.entries[index];
if (entry.used and !eql(entry.key, key)) {
if (entry.distance_from_start_index &lt; distance_from_start_index) {
// robin hood to the rescue
const tmp = *entry;
hm.max_distance_from_start_index = math.max(hm.max_distance_from_start_index,
distance_from_start_index);
*entry = Entry {
.used = true,
.distance_from_start_index = distance_from_start_index,
.key = key,
.value = value,
};
key = tmp.key;
value = tmp.value;
distance_from_start_index = tmp.distance_from_start_index;
}
continue;
}
if (!entry.used) {
// adding an entry. otherwise overwriting old value with
// same key
hm.size += 1;
}
hm.max_distance_from_start_index = math.max(distance_from_start_index, hm.max_distance_from_start_index);
*entry = Entry {
.used = true,
.distance_from_start_index = distance_from_start_index,
.key = key,
.value = value,
};
return;
}
unreachable // put into a full map
}
fn internalGet(hm: &amp;Self, key: K) -&gt; ?&amp;Entry {
const start_index = hm.keyToIndex(key);
{var roll_over: usize = 0; while (roll_over &lt;= hm.max_distance_from_start_index) : (roll_over += 1) {
const index = (start_index + roll_over) % hm.entries.len;
const entry = &amp;hm.entries[index];
if (!entry.used) return null;
if (eql(entry.key, key)) return entry;
}}
return null;
}
fn keyToIndex(hm: &amp;Self, key: K) -&gt; usize {
return usize(hash(key)) % hm.entries.len;
}
}
}
test "basic hash map test" {
var map: HashMap(i32, i32, hash_i32, eql_i32) = undefined;
map.init(&amp;debug.global_allocator);
defer map.deinit();
%%map.put(1, 11);
%%map.put(2, 22);
%%map.put(3, 33);
%%map.put(4, 44);
%%map.put(5, 55);
assert((??map.get(2)).value == 22);
map.remove(2);
assert(if (const entry ?= map.get(2)) false else true);
}
fn hash_i32(x: i32) -&gt; u32 {
*(&amp;u32)(&amp;x)
}
fn eql_i32(a: i32, b: i32) -&gt; bool {
a == b
}</code></pre>
<h3 id="tetris">Tetris Clone</h3>
<img src="tetris-screenshot.png">
<p>
<a href="https://github.com/andrewrk/tetris">Source Code on GitHub</a>
</p>
<h3 id="clashos">Bare Bones Operating System</h3>
<p>
<a href="https://github.com/andrewrk/clashos">Source Code on GitHub</a>
</p>
<h3 id="cat">Cat Utility</h3>
<pre><code class="zig">const std = @import("std");
const io = std.io;
const mem = std.mem;
const os = std.os;
pub fn main() -&gt; %void {
const exe = os.args.at(0);
var catted_anything = false;
var arg_i: usize = 1;
while (arg_i &lt; os.args.count()) : (arg_i += 1) {
const arg = os.args.at(arg_i);
if (mem.eql(u8, arg, "-")) {
catted_anything = true;
try cat_stream(&amp;io.stdin);
} else if (arg[0] == '-') {
return usage(exe);
} else {
var is = io.InStream.open(arg, null) catch |err| {
%%io.stderr.printf("Unable to open file: {}\n", @errorName(err));
return err;
};
defer is.close();
catted_anything = true;
try cat_stream(&amp;is);
}
}
if (!catted_anything) {
try cat_stream(&amp;io.stdin);
}
try io.stdout.flush();
}
fn usage(exe: []const u8) -&gt; %void {
%%io.stderr.printf("Usage: {} [FILE]...\n", exe);
return error.Invalid;
}
fn cat_stream(is: &amp;io.InStream) -&gt; %void {
var buf: [1024 * 4]u8 = undefined;
while (true) {
const bytes_read = is.read(buf[0..]) catch |err| {
%%io.stderr.printf("Unable to read from stream: {}\n", @errorName(err));
return err;
};
if (bytes_read == 0) {
break;
}
io.stdout.write(buf[0..bytes_read]) catch |err| {
%%io.stderr.printf("Unable to write to stdout: {}\n", @errorName(err));
return err;
};
}
}</code></pre>
<h3 id="multiline-strings">Multiline String Syntax</h3>
<pre><code class="zig">pub fn createAllShaders() -&gt; AllShaders {
var as : AllShaders = undefined;
as.primitive = createShader(
\\#version 150 core
\\
\\in vec3 VertexPosition;
\\
\\uniform mat4 MVP;
\\
\\void main(void) {
\\ gl_Position = vec4(VertexPosition, 1.0) * MVP;
\\}
,
\\#version 150 core
\\
\\out vec4 FragColor;
\\
\\uniform vec4 Color;
\\
\\void main(void) {
\\ FragColor = Color;
\\}
, null);
as.primitive_attrib_position = as.primitive.attrib_location(c&quot;VertexPosition&quot;);
as.primitive_uniform_mvp = as.primitive.uniform_location(c&quot;MVP&quot;);
as.primitive_uniform_color = as.primitive.uniform_location(c&quot;Color&quot;);
as.texture = createShader(
\\#version 150 core
\\
\\in vec3 VertexPosition;
\\in vec2 TexCoord;
\\
\\out vec2 FragTexCoord;
\\
\\uniform mat4 MVP;
\\
\\void main(void)
\\{
\\ FragTexCoord = TexCoord;
\\ gl_Position = vec4(VertexPosition, 1.0) * MVP;
\\}
,
\\#version 150 core
\\
\\in vec2 FragTexCoord;
\\out vec4 FragColor;
\\
\\uniform sampler2D Tex;
\\
\\void main(void)
\\{
\\ FragColor = texture(Tex, FragTexCoord);
\\}
, null);
as.texture_attrib_tex_coord = as.texture.attrib_location(c&quot;TexCoord&quot;);
as.texture_attrib_position = as.texture.attrib_location(c&quot;VertexPosition&quot;);
as.texture_uniform_mvp = as.texture.uniform_location(c&quot;MVP&quot;);
as.texture_uniform_tex = as.texture.uniform_location(c&quot;Tex&quot;);
debug_gl.assert_no_error();
return as;
}</code></pre>
<h3 id="mersenne">Mersenne Twister Random Number Generator</h3>
<pre><code class="zig">const assert = @import(&quot;debug.zig&quot;).assert;
const rand_test = @import(&quot;rand_test.zig&quot;);
pub const MT19937_32 = MersenneTwister(
u32, 624, 397, 31,
0x9908B0DF,
11, 0xFFFFFFFF,
7, 0x9D2C5680,
15, 0xEFC60000,
18, 1812433253);
pub const MT19937_64 = MersenneTwister(
u64, 312, 156, 31,
0xB5026F5AA96619E9,
29, 0x5555555555555555,
17, 0x71D67FFFEDA60000,
37, 0xFFF7EEE000000000,
43, 6364136223846793005);
/// Use `init` to initialize this state.
pub const Rand = struct {
const Rng = if (@sizeOf(usize) &gt;= 8) MT19937_64 else MT19937_32;
rng: Rng,
/// Initialize random state with the given seed.
pub fn init(r: &amp;Rand, seed: usize) {
r.rng.init(seed);
}
/// Get an integer with random bits.
pub fn scalar(r: &amp;Rand, comptime T: type) -&gt; T {
if (T == usize) {
return r.rng.get();
} else {
var result: [@sizeOf(T)]u8 = undefined;
r.fillBytes(result);
return ([]T)(result)[0];
}
}
/// Fill `buf` with randomness.
pub fn fillBytes(r: &amp;Rand, buf: []u8) {
var bytes_left = buf.len;
while (bytes_left &gt;= @sizeOf(usize)) {
([]usize)(buf[buf.len - bytes_left...])[0] = r.rng.get();
bytes_left -= @sizeOf(usize);
}
if (bytes_left &gt; 0) {
var rand_val_array : [@sizeOf(usize)]u8 = undefined;
([]usize)(rand_val_array)[0] = r.rng.get();
while (bytes_left &gt; 0) {
buf[buf.len - bytes_left] = rand_val_array[@sizeOf(usize) - bytes_left];
bytes_left -= 1;
}
}
}
/// Get a random unsigned integer with even distribution between `start`
/// inclusive and `end` exclusive.
// TODO support signed integers and then rename to &quot;range&quot;
pub fn rangeUnsigned(r: &amp;Rand, comptime T: type, start: T, end: T) -&gt; T {
const range = end - start;
const leftover = @maxValue(T) % range;
const upper_bound = @maxValue(T) - leftover;
var rand_val_array : [@sizeOf(T)]u8 = undefined;
while (true) {
r.fillBytes(rand_val_array);
const rand_val = ([]T)(rand_val_array)[0];
if (rand_val &lt; upper_bound) {
return start + (rand_val % range);
}
}
}
/// Get a floating point value in the range 0.0..1.0.
pub fn float(r: &amp;Rand, comptime T: type) -&gt; T {
// TODO Implement this way instead:
// const int = @int_type(false, @sizeOf(T) * 8);
// const mask = ((1 &lt;&lt; @float_mantissa_bit_count(T)) - 1);
// const rand_bits = r.rng.scalar(int) &amp; mask;
// return @float_compose(T, false, 0, rand_bits) - 1.0
const int_type = @intType(false, @sizeOf(T) * 8);
const precision = if (T == f32) {
16777216
} else if (T == f64) {
9007199254740992
} else {
@compileError(&quot;unknown floating point type&quot;)
};
return T(r.rangeUnsigned(int_type, 0, precision)) / T(precision);
}
};
fn MersenneTwister(
comptime int: type, comptime n: usize, comptime m: usize, comptime r: int,
comptime a: int,
comptime u: int, comptime d: int,
comptime s: int, comptime b: int,
comptime t: int, comptime c: int,
comptime l: int, comptime f: int) -&gt; type
{
struct {
const Self = this;
array: [n]int,
index: usize,
pub fn init(mt: &amp;Self, seed: int) {
mt.index = n;
var prev_value = seed;
mt.array[0] = prev_value;
{var i: usize = 1; while (i &lt; n) : (i += 1) {
prev_value = int(i) +% f *% (prev_value ^ (prev_value &gt;&gt; (int.bit_count - 2)));
mt.array[i] = prev_value;
}};
}
pub fn get(mt: &amp;Self) -&gt; int {
const mag01 = []int{0, a};
const LM: int = (1 &lt;&lt; r) - 1;
const UM = ~LM;
if (mt.index &gt;= n) {
var i: usize = 0;
while (i &lt; n - m) : (i += 1) {
const x = (mt.array[i] &amp; UM) | (mt.array[i + 1] &amp; LM);
mt.array[i] = mt.array[i + m] ^ (x &gt;&gt; 1) ^ mag01[x &amp; 0x1];
}
while (i &lt; n - 1) : (i += 1) {
const x = (mt.array[i] &amp; UM) | (mt.array[i + 1] &amp; LM);
mt.array[i] = mt.array[i + m - n] ^ (x &gt;&gt; 1) ^ mag01[x &amp; 0x1];
}
const x = (mt.array[i] &amp; UM) | (mt.array[0] &amp; LM);
mt.array[i] = mt.array[m - 1] ^ (x &gt;&gt; 1) ^ mag01[x &amp; 0x1];
mt.index = 0;
}
var x = mt.array[mt.index];
mt.index += 1;
x ^= ((x &gt;&gt; u) &amp; d);
x ^= ((x &lt;&lt;% s) &amp; b);
x ^= ((x &lt;&lt;% t) &amp; c);
x ^= (x &gt;&gt; l);
return x;
}
}
}
test "float 32" {
var r: Rand = undefined;
r.init(42);
{var i: usize = 0; while (i &lt; 1000) : (i += 1) {
const val = r.float(f32);
assert(val &gt;= 0.0);
assert(val &lt; 1.0);
}}
}
test "MT19937_64" {
var rng: MT19937_64 = undefined;
rng.init(rand_test.mt64_seed);
for (rand_test.mt64_data) |value| {
assert(value == rng.get());
}
}
test "MT19937_32" {
var rng: MT19937_32 = undefined;
rng.init(rand_test.mt32_seed);
for (rand_test.mt32_data) |value| {
assert(value == rng.get());
}
}</code></pre>
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@ -92,14 +92,16 @@ pub fn main() -> %void {
<p>For some discussion on the rationale behind these design decisions, see <a href="https://github.com/zig-lang/zig/issues/663">issue #663</a></p>
{#header_close#}
{#header_open|Values#}
<pre><code class="zig">const warn = @import("std").debug.warn;
const os = @import("std").os;
const assert = @import("std").debug.assert;
{#code_begin|exe|values#}
const std = @import("std");
const warn = std.debug.warn;
const os = std.os;
const assert = std.debug.assert;
// error declaration, makes `error.ArgNotFound` available
error ArgNotFound;
pub fn main() -&gt; %void {
pub fn main() -> %void {
// integers
const one_plus_one: i32 = 1 + 1;
warn("1 + 1 = {}\n", one_plus_one);
@ -137,30 +139,8 @@ pub fn main() -&gt; %void {
warn("\nerror union 2\ntype: {}\nvalue: {}\n",
@typeName(@typeOf(number_or_error)), number_or_error);
}</code></pre>
<pre><code class="sh">$ zig build-exe values.zig
$ ./values
1 + 1 = 2
7.0 / 3.0 = 2.333333
false
true
false
nullable 1
type: ?[]const u8
value: null
nullable 2
type: ?[]const u8
value: hi
error union 1
type: %i32
value: error.ArgNotFound
error union 2
type: %i32
value: 1234</code></pre>
}
{#code_end#}
{#header_open|Primitive Types#}
<table>
<tr>
@ -3630,17 +3610,18 @@ fn sum(numbers: []i32) -&gt; i32 {
{#header_close#}
{#header_open|Case Study: printf in Zig#}
<p>
Putting all of this together, let's seee how <code>printf</code> works in Zig.
Putting all of this together, let's see how <code>printf</code> works in Zig.
</p>
<pre><code class="zig">const warn = @import("std").debug.warn;
{#code_begin|exe|printf#}
const warn = @import("std").debug.warn;
const a_number: i32 = 1234;
const a_string = "foobar";
pub fn main(args: [][]u8) -&gt; %void {
pub fn main() {
warn("here is a string: '{}' here is a number: {}\n", a_string, a_number);
}</code></pre>
<pre><code>here is a string: 'foobar' here is a number: 1234</code></pre>
}
{#code_end#}
<p>
Let's crack open the implementation of this and see how it works:
@ -3760,15 +3741,17 @@ pub fn printf(self: &amp;OutStream, comptime format: []const u8, args: ...) -&gt
Zig doesn't care whether the format argument is a string literal,
only that it is a compile-time known value that is implicitly castable to a <code>[]const u8</code>:
</p>
<pre><code class="zig">const warn = @import("std").debug.warn;
{#code_begin|exe|printf#}
const warn = @import("std").debug.warn;
const a_number: i32 = 1234;
const a_string = "foobar";
const fmt = "here is a string: '{}' here is a number: {}\n";
pub fn main(args: [][]u8) -&gt; %void {
pub fn main() {
warn(fmt, a_string, a_number);
}</code></pre>
}
{#code_end#}
<p>
This works fine.
</p>
@ -4943,8 +4926,9 @@ test "wraparound addition and subtraction" {
<p>At runtime crashes with the message <code>attempt to unwrap null</code> and a stack trace.</p>
<p>One way to avoid this crash is to test for null instead of assuming non-null, with
the <code>if</code> expression:</p>
<pre><code class="zig">const warn = @import("std").debug.warn;
pub fn main() -&gt; %void {
{#code_begin|exe|test#}
const warn = @import("std").debug.warn;
pub fn main() {
const nullable_number: ?i32 = null;
if (nullable_number) |number| {
@ -4952,10 +4936,8 @@ pub fn main() -&gt; %void {
} else {
warn("it's null\n");
}
}</code></pre>
<pre><code class="sh">% zig build-exe test.zig
$ ./test
it's null</code></pre>
}
{#code_end#}
{#header_close#}
{#header_open|Attempt to Unwrap Error#}
<p>At compile-time:</p>
@ -4975,9 +4957,10 @@ fn getNumberOrFail() -&gt; %i32 {
<p>At runtime crashes with the message <code>attempt to unwrap error: ErrorCode</code> and a stack trace.</p>
<p>One way to avoid this crash is to test for an error instead of assuming a successful result, with
the <code>if</code> expression:</p>
<pre><code class="zig">const warn = @import("std").debug.warn;
{#code_begin|exe|test#}
const warn = @import("std").debug.warn;
pub fn main() -&gt; %void {
pub fn main() {
const result = getNumberOrFail();
if (result) |number| {
@ -4989,13 +4972,10 @@ pub fn main() -&gt; %void {
error UnableToReturnNumber;
fn getNumberOrFail() -&gt; %i32 {
fn getNumberOrFail() -> %i32 {
return error.UnableToReturnNumber;
}</code></pre>
<pre><code class="sh">$ zig build-exe test.zig
$ ./test
got error: UnableToReturnNumber</code></pre>
}
{#code_end#}
{#header_close#}
{#header_open|Invalid Error Code#}
<p>At compile-time:</p>